CDS Full Form: Combined Defence Services Exam Complete Guide

CDS Full Form: Combined Defence Services Exam Complete Guide

CDS stands for Combined Defence Services. The Combined Defence Services Examination is conducted by UPSC twice a year as a gateway to four Officer Training Academies of the Indian Armed Forces: Indian Military Academy (IMA), Indian Naval Academy (INA), Air Force Academy (AFA), and Officers’ Training Academy (OTA).

Unlike NDA, which targets Class 12 students, CDS is for graduates. If you’ve completed your bachelor’s degree and want an officer’s commission in the armed forces, CDS is your primary route.

CDS Full Form and What the Exam Covers

The Combined Defence Services Examination is “combined” because a single exam serves as the written filter for multiple defence academies and services. You appear for one exam, clear it, and then choose your academy based on your preference and merit.

UPSC conducts CDS I (notified in October/November, held in February) and CDS II (notified in May/June, held in September) every year.

Four Academies Under CDS

IMA, INA, and AFA lead to Permanent Commission (PC) — a full career in the armed forces. OTA leads to Short Service Commission (SSC) — initially 10 years (extendable to 14 years), with the option to apply for PC during service.

OTA also has a separate women’s division in Chennai for SSC (Women Non-Technical).

CDS Exam Pattern

The CDS exam has different paper structures for IMA/INA/AFA versus OTA.

For IMA, INA, and AFA

For OTA (Men and Women)

OTA candidates don’t write Mathematics. This makes OTA slightly more accessible.

Negative Marking

Like all UPSC exams, CDS has negative marking: one-third of the marks assigned to a question are deducted for each wrong answer. Don’t guess blindly.

Nature of Questions

• English: Reading comprehension, grammar, sentence correction, ordering of sentences, vocabulary
• General Knowledge: Current events, history, geography, Indian polity, economy, science (basic Physics, Chemistry, Biology)
• Mathematics: Arithmetic, algebra, trigonometry, geometry, statistics — up to Class 10 level only

The Mathematics paper for CDS is limited to Class 10 standard. But don’t underestimate it — accuracy and speed matter, and the breadth of topics requires solid fundamentals.

CDS Eligibility: Who Can Apply

Eligibility varies by academy. This is where many aspirants trip up.

Key differences to note:

• INA and AFA require Physics and Mathematics at degree level
• OTA allows married candidates (for both men and women)
• AFA age limit is 20–24, slightly different from IMA/INA

Physical Standards

Like NDA, CDS candidates must meet physical standards:

• Minimum height: 157.5 cm for Army, 157 cm for Navy, 162.5 cm for Air Force (men)
• Minimum height: 152 cm for women
• Corrected vision requirements vary by service and branch

Medical standards are assessed at the SSB interview stage by service medical boards.

NDA Full Form: National Defence Academy Complete Guide

SSB Interview: The Real Test

Like NDA, the CDS written exam is only a qualifying filter. The SSB (Service Selection Board) interview is where selection actually happens. Written exam marks don’t count toward your final merit.

SSB Structure: 5 Days

Day 1 — Screening Stage:

• Officer Intelligence Rating (OIR) — verbal and non-verbal tests
• PPDT (Picture Perception and Discussion Test) — candidates view a vague image, write a story, then discuss in groups
• Only those who clear Day 1 continue. Others are sent back home.

Day 2 — Psychological Tests:

• TAT (Thematic Apperception Test) — write stories for 11 images
• WAT (Word Association Test) — write first thought for 60 words, 15 seconds each
• SRT (Situation Reaction Test) — write responses to 60 situations in 30 minutes
• Self Description Test — write what you think of yourself, what your parents/teachers think

Day 3–4 — GTO (Group Testing Officer) Tasks:

• Group Discussions (2 rounds)
• Group Planning Exercise
• Progressive Group Task, Half Group Task, Final Group Task — outdoor physical/problem-solving obstacles
• Individual Obstacles — 10 obstacles, 3 minutes
• Command Task — lead a small group through an obstacle (after individual interviews)
• Lecturette — 3-minute talk on a topic picked from 4 chits

Day 2–4 (parallel) — Personal Interview: The IO (Interviewing Officer) conducts a 30–45 minute personal interview covering your background, academics, interests, and officer potential.

Day 5 — Conference: All three assessors (Psychologist, GTO, IO) discuss each candidate. Candidates are called individually for a brief conference. Final selection is announced.

What SSB Assesses: Officer Like Qualities (OLQs)

SSB assesses 15 OLQs grouped under Effective Intelligence, Reasoning Ability, Social Adaptability, Communication, and Dynamism. You can’t fake these — assessors look for consistency across all tests over 5 days.

CDS Vacancies: How Many Get Selected?

Each CDS exam notifies vacancies for each academy. Typical numbers:

Total approximately 360–365 per CDS exam, or 720–730 per year.

About 4–5 lakh candidates appear for each CDS exam. Around 7,000–10,000 qualify the written stage and are called for SSB. The final selection rate from SSB is roughly 5–7%.

CDS vs NDA: Key Differences

Both exams are conducted by UPSC, but NDA is for younger candidates still in school/fresh out of Class 12.

UPSC Full Form: Union Public Service Commission Guide

Frequently Asked Questions